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Use of nondestructive spectroscopy to assess chlorophyll and nitrogen in fresh leaves

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dc.contributor Fuchigami, Leslie H.
dc.contributor Scagel, Carolyn
dc.contributor Linderman, Robert G.
dc.contributor Vasconcelos, Carmo M.
dc.contributor Young, John A.
dc.date 2006-01-03T20:51:35Z
dc.date 2006-01-03T20:51:35Z
dc.date 2005-12-05
dc.date 2006-01-03T20:51:35Z
dc.date.accessioned 2013-10-16T07:30:07Z
dc.date.available 2013-10-16T07:30:07Z
dc.date.issued 2013-10-16
dc.identifier http://hdl.handle.net/1957/784
dc.identifier.uri http://koha.mediu.edu.my:8181/xmlui/handle/1957/784
dc.description Graduation date: 2006
dc.description Four aspects of factors influencing the accuracy of nondestructive chlorophyll (Chl) and nitrogen (N) measurement in fresh leaves were studied: (1) optimum wavelength (OW) identification; (2) indices development and evaluation; (3) influence of leaf properties; and (4) influence of meter parameters and sampling technique. Results were used to develop indices and prototype meters for Chl and N assessment. Our results indicated that the simple linear coefficient of determination (R2) between spectral reflectance or transmission and Chl or N in combination with spectral sensitivity was the most reliable method for determining the OW for Chl and N measurement in fresh leaves. There were two ranges of wavelengths, one in visible region (550 - 580 nm) and the other in the red edge region (700 - 730 nm), we determined that had the highest spectral sensitivity and largest R2 with smallest root mean square error over a wide-range of Chl concentrations (160 – 1188 µmol.m-2), and could be used as the OW to develop indices for Chl and N assessment. The OW in the red edge region could be used for Chl assessment across all species tested and the OW in the visible region could be used across anthocyanins-free species. The best indices were the indices developed with the Chl-related OW either from visible or red edge region in combination with a reference wavelength (RW) from the near infrared (NIR) region (750 – 1100 nm) that was sensitive to leaf texture but insensitive to Chl as the form of a simple ratio (RRW/ROW) or normalized difference vegetation index (RRW – ROW)/( RRW + ROW). With RW, the differences in reflectance in the visible and red edge regions caused by variation in leaf texture or other optical properties could be eliminated. This was particularly important when the R2 of a single-wavelength index was small for Chl or N measurement (e.g. R2<0.8000 for Chl or R2<0.6000 for N). Parameters used by hand-held Chl meters (CCM-200, SPAD-502, and CM-1000) affected their accuracy for Chl and N assessment. Our results showed that SPAD-502 was more accurate than CCM-200 and CM-1000 for assessing Chl and N in fresh leaves. The Chl-sensitive wavelength used by CM-1000 (700 nm) was more accurate for estimating Chl than the wavelengths used by SPAD-502 (650 nm) and CCM-200 (660nm); however, we found that variation in sampling distance, orientation, light intensity, and the inconsistency of light intensity between ambient light sensor and the target leaf made the CM-1000 less accurate than the other two meters. Using the indices and OW determined through our research, we developed three prototype meters that were more accurate than or similar to the commercial hand-held meters in measuring Chl or N in fresh leaves. Among them, the prototype-III was more accurate than all the commercial hand-held meters for Chl and than the CM-1000 for N assessments across all the species we tested.
dc.language en_US
dc.subject chlorophyll
dc.subject nitrogen
dc.subject assessment
dc.subject wavelength
dc.subject optimum wavelength
dc.subject reference wavelength
dc.subject near infrared region
dc.subject visible region
dc.subject spectroradiometor
dc.subject reflectance sensitivity
dc.subject simple linear regression coefficient determination
dc.subject root mean square error
dc.subject chlorophyll-sensitive wavelength
dc.subject chlorophyll-insensitive wavelength
dc.subject 1st derivative
dc.subject index
dc.subject hand-held meter
dc.subject nondestructive
dc.title Use of nondestructive spectroscopy to assess chlorophyll and nitrogen in fresh leaves
dc.type Thesis

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